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Abstract

Reserva Natural Absoluta Cabo Blanco, located at the southern tip of northwestern Costa Rica’s Nicoya Peninsula, was established in 1963 and is the country’s oldest nationally protected reserve. Because the climate of the Nicoya Peninsula is ideal for human habitation, the peninsula has been occupied for millennia and is a heavily impacted landscape. The region also is one of the most poorly studied in Central America in terms of biotic diversity. We initiated a multiyear survey of bats in the reserve and the adjacent Refugio de Vida Silvestre Cueva Los Murciélagos to quantify species diversity, abundances, habitat use, seasonality, and reproduction. By surveying bats during 5 rainy seasons and 4 dry seasons from July 1999 through February 2006, we address the following questions: Which species of bats are present in the area? Are the bat communities the same in 3 different habitats—coastal forest, inland forest, and limestone caves? Are the species diversity and abundances of bats in the rainy season similar to those in the dry season? Can we discern seasonal patterns of reproduction? Are the species diversity and abundances of bats at Cabo Blanco (a tropical moist forest in the Holdridge Life Zone classification) similar to those in the nearby tropical dry forest at Parque Nacional Palo Verde? What are the conservation implications of the bat assemblages found in this regenerating forest?
Using mist nets, searching for roosting bats, and an acoustical survey, 39 species of bats are documented in the area, including 5 emballonurids, 4 molossids, 1 mormoopid, 1 noctilionid, 21 phyllostomids, and 7 vespertilionids. The 2 most commonly captured bats, Carollia perspicillata and Artibeus jamaicensis, are abundant in both the inland and coastal forests and both are more abundant in the rainy season than in the dry season. Several species have clear habitat preferences, at least during the seasons in which we netted (Glossophaga soricina and Uroderma bilobatum along the coast and Trachops cirrhosus inland). The largest carnivores (Noctilio leporinus, Chrotopterus auritus, Phyllostomus hastatus, Trachops cirrhosus, and Vampyrum spectrum) are present, but the small and middle-sized predatory bats (Micronycteris, Lophostoma, and others) are poorly represented both in terms of diversity and abundance. We captured twice as many bats per hour of effort in the inland forest as we did in the coastal forest. The caves of Refugio de Vida Silvestre Cueva Los Murciélagos have 4 species of bats (Balantiopteryx plicata, Saccopteryx bilineata, Desmodus rotundus, and Phyllostomus hastatus) that are year-round residents.
Several species seem to be equally abundant in both seasons, including Balantiopteryx plicata, Saccopteryx bilineata, Noctilio leporinus, Artibeus watsoni, Desmodus rotundus, Glossophaga soricina, Phyllostomus hastatus, Trachops cirrhosus, Lasiurus ega, and Myotis nigricans. Our impression is that some species are more common during the rainy season than the dry season, but more data are needed to substantiate this assertion. Bats in the caves were equally abundant during each of our 8 cave surveys. Desmodus rotundus is the only species for which our data suggest year-round reproduction; we observed scrotal males, pregnant females, and juveniles during each of our visits to Cabo Blanco. Other species are present year-round but have seasonal reproductive activity. We captured Artibeus watsoni and Carollia perspicillata in both seasons but have seen pregnant females only during the rainy season.
Carollia perspicillata and Artibeus jamaicensis are the 2 most commonly captured bats at both Cabo Blanco and the nearby Parque Nacional Palo Verde. The species records and abundances of several other species differed between the sites, however. Species that are abundant at Palo Verde, but not yet recorded from Cabo Blanco, include Pteronotus davyi, Pteronotus gymnonotus, Carollia subrufa, Centurio senex, and Natalus stramineus. Phyllostomus hastatus is abundant at Cabo Blanco but not known from Palo Verde. Although both sites are relatively close together in the northern Pacific lowlands of Costa Rica, Cabo Blanco is substantially wetter, and the associated differences in vegetation may be driving bat distributional patterns.
We provide a number of new records and ecological information for bats on the Nicoya Peninsula and document that bat diversity and abundances can be substantial in regenerating forest. Several of the most commonly captured bat species are seed dispersers and may be critical to forest regeneration.